Plaster board



Sept. 20, 1927.

- 1,642,840 s, c. CLARK PLASTER BOARD Filed Jan. 6, 1922 .ZZ LLLZTIfO Sen/" 1 W M.m@# y Patented Sept; 1927.

sinner cfor nK, or Ponrr omurom-onro, ASSIGNOR T AMERICAN GYPSUM colut nny, or roar ctrn'ron, OHIO, A oonronarron or onro.

" PLASTER am).

Applicationfi led January 6, 1922. Serial No. 527,324..

This invention relates to improvements in plaster board and more particularly to an improved method of. constructing plaster board so as to provide a iiioieclula ble' and stronger product, these qualities not being confinedto its Characteristics as a wall constructing material but also its ability to resist breakage and damage in the handling incident to-its manufacture and transporta- Lion-prior to its ultimate application upon a wall structure.

The novel features of the invention p ertainimore especially to the manner m which theedges are treated in order to secure the advantages of uniformand smooth finish,

and marginal strength and resistance againstdamage at handlin The treatment of the edges, ordinarily referred to as sealing or binding, involves a process of manufacture vwhereby the margms of the covering sheets of fibrous material are folded 'over the edges of the body of plaster in a novel manner-"calculated to produce advantages not found in plaster. board manufactured by processes now in use. Theconstruction'of the plaster board or method of binding the edges thereof is hereinafter described in detail, and illusstruction of the walls of buildings and as ordinarily manufactured, consists of a layer of plaster superimposed between sheets of heavy paper or other fibrous material, the latter providing the qualities of durability and toughness that is completely lacking in the plaster, thereby enabling the product to be marketed in the form of sheets, ready to be nailed or otherwise applied to the wall structure. As herembefore suggested, a sheet of plaster board comprises a body 1 of plaster of the desired thickness, a jbottom covering sheet 2 of tough paper or other fibrous material, anda similar top covering sheet As will hereinafter appear, the treatment of both the 'bottomand top covering sheets is identical, therefore, it is to be understood that the distinction is one of convenience only in describing the product, as illustrated.

'l'he covering sheets 2 and 3 are somewhat wider than the body 1, being provided with marginal strips44, which extend beyond the edges of said body and constitute the parts utilized in the formation of the edgesof the .finished product. -These marginal portions 4-4, although integral with the covering sheets. are preferably to be considered separate therefrom for the purpose of a clearer understanding of the structure, and forthe same reason, each of the mar-' gin-a1 portions -l4 will be considered as consisting of two parts, presently to be in 'dicated.

Considering one of the edges', and with particular regard to the process by which the edge is formed, the marginal portions 4-4 being folded inwardly and toward each other at right angles to theirjrespectivef sheets 2 and 3, against the. exposed edge surface of said body along fold lines 55, for

a distance substantially equal to one-third the thickness of the body 1, forming. what may be termed end strips 66.' At the extremity: of the end strips the remaining portions or flaps 7-7 are folded again at right angles to the end strips along fold lines 88, and extend edgewise into the body, parallel with each other and to the main sections of the covering sheets. words, each marginal flap 4 is folded twice at right angles, once against the edge, and

again at right angles to the edge so that the marginal flap 7 is embedded in the body 1. The length of the marginal flaps or embedded edges 7-7 of the covering sheets may be varied, although preferably extending inwardly from the edge of the board a distance sufficient to provide marginal areas of ample width througl'i which the nails may be driven in applying the. board to a wall.

In practice, the plaster in plastic state is applied to the bottom sheet, the upper sheet applied, and the margins folded in substantially final form prior to the passage between rolls, whereby the plastic material is spread evenly and to a uniform thickness throughout the width of the board, filling the spaces between the flaps 77 and the outer sections of the sheets, as Well as the space between the flaps themselves in the form of a com paratively thin layer 9, extending outwardly In other lUt to and flush with the edge surface of the board and the edge" strips t -6 of the covering sheets. The exposed edges of the layer 9 are finished in order to provide a smooth edge surface throughout. As a preferred construction, the flaps 7-7 are spaced froin the outer surface coverings, a distance substantially equal to one-thirdthe thickness of the body, thus the thickness of the layer 9 9- of the body would besubstantially equal to one-third of its total thichnezs. However, these proportions may be varied to some extent, as for instance, the flaps 7- 7 maybe brought more nearly together and ver thin la er of Jlaster se aaratin thenr indeed: the actual contact of the flaps, and the ab sence'of an intermediate layer of plasten would be a A satisfactory construction;

It isto be observed that in constructing plasterboard in this manner the top and bottour sheets are independently treated in forming'the sealed; edges, that is to say, no

overlappingmr joiningof the sheets is re sorted to int-he scaling: operation, each sheet, on: the; otherflhand,be1ng anchored or enrbedded independently of the other in; the

body withnoed'ges exposed or joints-appearing: onthe surface of: the board. Itfollows, therefore, that: both sidesv of the board are identical inevery respect, and smoothly finished throughout.

The iniprovedg structure has special advantages pertaining tothe-quality or the product: as a building material. In the-first place, the embedded margins of the sheets not only form apermanent connection between the parts, but spacedas they are throiighout the thickness of the body, and extending along the edges thereof,'provide layers of reinforcement not only acting to provide a firmer edge, as a protection against injury in handling, but as a means for insuring a more permanent and tenacious adherence of the board to the wall structure inasbe variously modified Without departing from the spirit of the-invention, and therefore',l do not wish to belimited except inse far'as the invention; is specifically set forth inthe appended claim; I a r I- claim as my invention;

A plasterboard eon1prisinga plaster body hating covering sheets adheringto the" op- J posite faces thereof, and; folded over; the

junctions of the side edges and faces there,

of, and foldedfiagain into and embedded; in the plaster body in spacedrelationsoasto expose a portionthereof-along the side edges of said plaster board. p a

In witness whereof, I hereuntosubscribe m name this 30th day of Dece1nber,-A. D.,

1921. v W SIDNEY C. CLARK. 

